I. Field of the Invention
This invention relates to luggage carriers adapted to be mounted to a vehicle surface and, in particular, to an adjustable cross rail for forming a suspended load-bearing rack for the luggage carrier.
II. Description of the Prior Art
Luggage racks mounted to the exterior surface of automotive vehicles have long been utilized to transport luggage exteriorly of the vehicle. The simplest form of luggage carrier is constructed of a series of parallel slats mounted flush with the top of the vehicle. These slats are designed to provide extra support while preventing damage to the roof top. However, these racks lack means for constraining the baggage which oftentimes resulted in lost luggage as it slid off the rack.
In order to overcome this disadvantage, an elevated frame was added which prevented the baggage from sliding off of the carrier due to changes in momentum. This frame generally extends about the peripheral edge of the slats which support the luggage and is supported above the vehicle surface by stanchions mounted to the roof top. Although providing support and constraint of a majority of articles, it was found that heavier packages tended to cause the support slats and the roof top to bow under the weight. However, because of vehicle weight and aerodynamic constraints, support racks manufactured from heavier materials were undesirable. Moreover, the separate assembly and mounting of the peripheral frame and support rack increased production costs.
As a result, elevated racks were developed which did not depend on the support of the vehicle top. Moreover, since these luggage carriers could be assembled prior to mounting, manufacturing and assembly costs were reduced. Generally, these elevated racks do not include any peripheral constraint and therefore may cause loss of luggage. However, more recently elevated carriers which employ a suspended load-bearing rack have been developed. The load-bearing rack of these carriers is generally suspended from the peripheral frame yet space above the vehicle surface. With this construction, heavier packages may cause the cross rails of the rack to bow slightly without contacting or causing damage to the surface of the vehicle. Moreover, this elevated construction provides improved aerodynamics by allowing air to travel beneath the luggage across the vehicle top. However, the suspended cross rails are generally fixedly secured to the side rails of the frame and, therefore, do not provide means for adjusting the distance between the rails for luggage or packages of different sizes and weights. In addition, the fixed cross rails do not allow for removal of the suspended rack during periods of non-use.
In order to provide such flexibility, adjustable cross rails were developed which clampingly engage a portion of the fixed side rail of the frame. However, in the past known adjustable cross rails, the clamping mechanism is secured to a protruding surface of the rail thereby increasing manufacturing costs. Thus, these clamping devices are designed to cooperate only with specially manufactured frames. Moreover, these known cross rails cannot be interchanged or utilized on luggage carriers having frame members with a non-standard diameter.